Cupin-Type Phosphoglucose Isomerases (Cupin-PGIs) Constitute a Novel Metal-Dependent PGI Family Representing a Convergent Line of PGI Evolution

Abstract

Cupin-type phosphoglucose isomerases (cPGIs) were identified in some archaeal and bacterial genomes and the respective coding function of cpgi's from the euryarchaeota Archaeoglobus fulgidus and Methanosarcina mazei, as well as the bacteria Salmonella enterica serovar Typhimurium and Ensifer meliloti, was proven by functional overexpression. These cPGIs and the cPGIs from Pyrococcus and Thermococcus spp. represent the cPGI family and were compared with respect to kinetic, inhibitory, thermophilic, and metal-binding properties. cPGIs showed a high specificity for the substrates fructose-6-phosphate and glucose-6-phosphate and were inhibited by millimolar concentrations of sorbitol-6-phosphate, erythrose-4-phosphate, and 6-phosphogluconate. Treatment of cPGIs with EDTA resulted in a complete loss of catalytic activity, which could be regained by the addition of some divalent cations, most effectively by Fe 2؉ and Ni 2؉ , indicating a metal dependence of cPGI activity. The motifs TX 3 PX 3 GXEX 3 TXGHXHX 6-11 EXY and PPX 3 HX 3 N were deduced as the two signature patterns of the novel cPGI family. Phylogenetic analysis suggests lateral gene transfer for the bacterial cPGIs from euryarchaeota.Phosphoglucose isomerase (PGI; EC 5.3.1.9) catalyzes the reversible isomerization of glucose-6-phosphate to fructose-6-phosphate. PGI plays a central role in sugar metabolism of eukarya, bacteria, and archaea, both in glycolysis via the Embden-Meyerhof pathway in eukarya and bacteria and in its modified versions found in archaea. PGI is also involved in gluconeogenesis, where the enzyme operates in the reverse direction (see references 22, 26, and 40). PGIs have evolved convergently. Most PGIs belong to the PGI superfamily, which can be divided into the PGI family and the recently identified bifunctional phosphoglucose/phosphomannose isomerase (PGI/PMI) family (22). PGIs from the PGI superfamily, often referred to as conventional PGIs, are found in all domains of life and are well studied. Crystal structures have been determined for the eukaryotic PGIs from pigs, rabbits, humans and from the bacterium Bacillus stearothermophilus, and conserved amino acids proposed to be involved in substrate binding and/ or catalysis have been identified (3, 6, 10-13, 28, 29, 42). Bifunctional PGI/PMIs, which have been characterized as a novel family within the PGI superfamily, were predominantly found in the crenarchaeotal branch of the archaea (26).Recently, a novel type of PGI has been identified and characterized from the hyperthermophilic euryarchaeon Pyrococcus furiosus (22, 52) and later from the closely related Thermococcus litoralis (30). These PGIs belong to the cupin superfamily and thus represent a convergent line of PGI evolution. The cupin superfamily is present in all three domains of life-eukarya, bacteria, and archaea-and comprises a group of functionally diverse proteins that contain a central domain composed of ␤-strands forming a small ␤-barrel called "cupin."Proteins from the cupin superfamily range, for example, from manno...

Carbohydrate Metabolism in Archaea: Current Insights into Unusual Enzymes and Pathways and Their Regulation

“…litoralis, Arc. fulgidus, and Methanosarcina mazei has been shown to be catalyzed by metalcontaining enzymes specific for G6P/F6P (74,(88)(89)(90). The coding sequences did not show any homology to conventional PGIs but were instead identified as members of the novel cupin-type PGI (cPGI) family within the cupin superfamily, which harbors functionally diverse members of all three domains of life.…”

“…However, with the missing sequence similarity/ homology, the metal dependence, and the completely different overall fold, cPGI clearly represents a different and novel type of metal-dependent PGI and, thus, a convergent line of PGI evolution (74). cPGIs have also been identified in some Bacteria, such as Ensifer meliloti and Salmonella enterica serovar Typhimurium, which has been explained by lateral gene transfer from Euryarchaeota, i.e., Thermococcales and Archaeoglobales, respectively (74).…”

“…4). In contrast to conventional PGIs, cPGI activity is strictly dependent on bivalent metal ions such as Fe 2ϩ and Ni 2ϩ (74,93). Two different catalytic mechanisms, proceeding via (i) a carbocation and a subsequent hydride shift and (ii) a cis-enediolate intermediate with a conserved glutamate residue (E97) as a base catalyst, as described above, have been proposed (94)(95)(96).…”

Allozyme variation in a natural population of Stryphnodendron adstringens in the Rio Preto State Park, southeastern Brazil

“…The anodal (pgi-2) locus showed a banding pattern typical of monomeric enzymes. Although a monomeric pattern of PGI has been observed in microorganisms such as Archaeoglobus fulgidus and Methanosarcina mazei (Hansen et al 2005), this enzyme is generally dimeric (Cini et al 1988, Tekamp-Olson et al 1988, Sun et al 1990. IDH gels of leaves and seeds demonstrated an activity zone controlled by a locus (idh-1) with three alleles.…”

Molecular cloning and characterization of TK1111, a cupin-type phosphoglucose isomerase from Thermococcus kodakaraensis

“…A third and a novel type of PGI has been found in euryarchaeotal branch of archaea [1,3,4] and it belongs to the cupin-family comprising a group of functionally diverse proteins that contain a central domain forming a small barrel called "cupin." Most of the cupin enzymes are metallo enzymes having two conserved sequences(consensus, G(X) [5][6][7][8] H(X)H(X) [3][4][5][6] E(X) 6 G, motif I; and G(X) 5 P(X) 4 H(X) 3 N, motif II)The PGIs belonging to this group have been characterized from archaea including Archaeoglobus fulgidus [5], Methanosarcina mazei [5], Pyrococcus furiosus [1,3], and Thermococcus litoralis [4] as well as from bacteria including Salmonella enterica and Ensiferm eliloti [5]. Determination of active-site residues of PGI from P. furiosus has been accomplished by docking of monosaccharides onto the structure models of the enzyme [6].…”